(1) Field of the Invention
The present invention relates to an automatic transmission which is suitable as a vehicular transmission mechanism for which multi-stage demand of gear shift stages and widening demand of a gear ratio width are present.
(2) Description of Related Art
A Japanese Patent Application First Publication No, 2001-182785 published on Jul. 6, 2001 exemplifies a previously proposed automatic transmission achieving respective gear shift stages of eight forward speeds (speed ratios) by means of three planetary gearsets and six frictional elements and which is provided with a double pinion planetary gearset, a Ravineaux planetary gear unit (one double pinion planetary gearset and one single pinion planetary gearset), four clutches, and two brakes.